1. Field of the Invention
The invention relates to a tool insertable within a subterranean well comprising a seal means defined by a continuous series of transversely compressible interlocking ductile metal-containing loop members.
2. Description of the Prior Art
During certain operations in a subterranean oil or gas well, such as during a completion or workover procedure, it is common practice to utilize a packer assembly, bridge plug or other isolation tool to separate one section or zone of a well from another section or zone. Such apparatuses typically employ elastomeric sealing members, utilized alone or in combination with other sealing elements, such as virgin tetrafluoroethylene and/or glass-filled tetrafluoroethylene components (sometimes referred to under the tradename "Teflon"), as the primary means for isolating the section or zone, the seal means, upon manipulation of the tool, sealing against the internal wall of the casing. In extremely hostile well environments, such as those wherein the bottom hole temperature is in excess of about 350.degree. F. and/or exposed to considerably high concentrations of H.sub.2 S and or CO.sub.2, an acrylonitrile-type elastomeric substance has been utilized in the seal means of the tool, to provide somewhat effective working life for the tool. The use of such acrylonitrile-type elastomers is not entirely satisfactory because this material can, with time, chemically degrade to the extent that its elastomeric properties are lost in the hostile environment, described above, Other materials, such as tetrafluoroethylene have the desired chemical inertness, but tend to extrude under high temperature and pressure. Additionally, when metallic back-up rings are utilized in such seal systems, wherein a gap is defined in the metallic ring upon expansion thereof into engagement with the casing, "gaps" or "voids" will be necessarily defined at one or more points thereon which require sealing with respect to the casing in order to insure the integrity of the entire seal system.
The present invention is directed to a seal means for use in a well tool, such as a well packer, which prevents extrusion of such inert sealing elements, described above, and which will fill "gaps" and "voids" within metallic back-up rings within the seal system.